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IEC 60398: Industrial Electroheating Equipment — Energy Efficiency Assessment From Induction Melting to Resistance Heating
Industrial Electric Heating Efficiency Is Not Just 100% Minus Heat Loss — There Are Deeper Physics Limits
IEC 60398:2015 specifies industrial electroheating equipment energy efficiency assessment. The theoretical efficiency of electric heating is 100% (all electrical energy becomes heat), but actual useful energy utilization is far lower — because the heat must transfer to the workpiece, and every transfer mechanism has inherent losses.
| Technology | Frequency/Mechanism | Typical Efficiency | Materials |
|---|---|---|---|
| Resistance | DC/50Hz, Joule heating | 60–90% | Metal melting, heat treatment furnaces |
| Induction | 50Hz–1MHz, eddy current + hysteresis | 50–85% | Steel, cast iron, Cu, Al |
| Arc | DC/50Hz, arc radiation + convection | 40–70% | EAF steelmaking |
| Microwave | 915MHz/2.45GHz, dielectric loss | 50–80% | Ceramics, food, rubber |
The induction heating skin-depth limit: induced current concentrates within the skin depth δ = √(2ρ/ωμ). Higher frequency → shallower penetration. For large-diameter steel billets (>200 mm), no matter how much power is applied, the core can only heat via conduction — induction heating efficiency has a fundamental physics ceiling. This is why large workpieces typically use low-frequency induction (50–150 Hz) to increase penetration depth.
TNLab — Electric heating efficiency depends on “how heat transfers from the source to the workpiece,” not just “how electricity becomes heat.”
